Combines commonly include yield monitors to determine desired properties of agricultural products as they are harvested. A typical yield monitor includes sensors, such as a mass-flow sensor and a moisture sensor. To obtain an accurate measurement of yield, the mass-flow sensor and moisture sensor must be periodically calibrated. The procedure for calibrating a mass-flow sensor normally involves harvesting grain, filling a grain cart, truck, or semi trailer, and comparing the measured weight with a more accurate weight obtained from a grain cart with a weighing system or from a certified truck scale.
One problem with prior art calibration techniques is that when a truck or trailer travels to a remote scale, a significant amount of time may elapse between the start of the calibration procedure and the end. In addition, a farmer may hesitate to stop harvesting while waiting to receive the actual weights from the calibration load. During the time that the trucks are away from the field, the calibration factor for the mass-flow sensor could be off significantly. Grain carts that are equipped with a weighing system can be used to more easily and quickly manually calibrate a mass-flow sensor. However, many grain carts are not equipped with a weighing system because they do not add significant value to the system.
In either case, the actual calibration load weight requires a manual entry into a display device (such as a GreenStar Display device). The manual entry of calibration information takes time for the operator. In addition, if the operator does not calibrate frequently, the accuracy of the mass-flow sensor can decrease since the load is based on a larger average and not the latest field conditions. Typically, it is considered too time-consuming to manually update the calibration factor after every load.